a few things to note with wireless..and no im not a guru
1, research cantenas and directional wireless, you can get a lot more distance out of a directional antenna than from a conventional "spam the world" wireless setup
2, What are you wanting to get to via wireless, do you want to play a game/leech off your neighbour or get free net acces. Justremember that someone has to pay for your internet usage (and will notice Gb's of data usage if your a leecher) should you find a node with net access.
3, All smart admins with wifi setups will use both encryption and also have specific ip ranges that are allowed onto their network (not all admins are smart hence wardriving still exists)
4, Changing frequencies "shouldnt" be necessary as the frequencies are allocated by A.C.A. ...au communications authority.
5, If ya find a nice wifi node, mark your acces point with yellow chalk, a big X should do, then inform good old uncle leppy of your findings, coz im yet to wardrive in darwin :D heheh
As has allready been stated you may be able to get to a node, yet find you need a login etc, dont expect the first network you find to let you on.
Also dont forget as mentioned in my 2nd point someone out there has paid for both the wifi setup and its bandwidth, nothing is free in this day and age, so expect to find a few networks, but dont think just coz you have a wifi card you will have free net or even have access to the local net unless you ask the admin/owner for permission/ip/login/encryption key etc.
P.S. final note, that you must know (but can ignore, and most ppl do) just coz its insecure and open does NOT mean you are allowed to use it. WiFi use is NOT immune to theft/fraud/hacking laws. You may be harder to catch, but your still breaking the law if you enter a network and or steal bandwidth.